Various slings and bandages have been employed for supporting the forearm of a patient who has had an injury or disability, particularly stroke victims. Current slings in use are static shoulder immobilizers. Total immobilization provided by these splints does adequately protect the glenohumeral joint but does nothing to promote return of normal function to stroke patients and due to their particular muscular imbalances can create additional problems.
Current splints or bandages hold the humerus in an abducted and extended position, the elbow is held at 90.degree. flexion or more and provide little or no support at the wrist or hand. This positioning decreases the effect gravity would have on the sensory receptors within the musculature that normally protects the joint. Any decrease in sensory input to the involved joint decreases normal facilitory effects and may even inhibit normal muscular function.
An abnormal flexion synergy described by Signe Brunnstrom in Movement Therapy in Hemiplegia generally develops in these patients. Current splints and slings do nothing to decrease this spasticity and due to lack of support at the wrist and hand can lead to the development of contractures due to prolonged positioning of the wrist and fingers in a flexed position. In addition, no splints or slings on the market for use in protecting the glenohumeral joint provide for support of the palmar arch or the web space of the hand. This lack of support or protection can lead to destruction of the palmar arch, leading to pain and decreasing the patient's ability to have a strong, functional grasp. In addition, these splints and slings do not maintain the thumb in a position of abduction and opposition which results in the web space tending to tighten and lose its normal elasticity.
Patents known to me relating to bandages and splints are U.S. Pat. Nos. 390,176, to Lee for a Surgical Splint; 2,800,129, to H. Van Swaay for a Method of Forming Splints; and 3,815,588, to Bracha Klausner for Apparatus and Methods Relating to Support of the Forearm. In general, the splints and apparatus and methods disclosed in these patents are unsatisfactory for a number of reasons. For example, the Klausner patented structure is resilient and semi-rigid and thereby deformable by the pressure by the action of spastic or hypertonic muscles in the forearm or hand. Such muscles often exert pressure greater or at least equal to the weight of the forearm and hand. Current research supports the hypothesis that continuous firm pressure over the muscle bellies of spastic muscles will tend to inhibit or decrease the tonus of the muscle by affecting the gamma loop while materials which are resilient tend to increase spasticity. The Klausner's patent also holds the forearm in a pronated position. In hemiplegic patients, the flexion spasticity which commonly dominates in the involved upper extremity includes pronation, and thus does not lessen the possibility of a joint contraction in the pronated position. Also, in the Klausner support the shoulder and elbow are immobilized which prevents exercising the shoulder and elbow and decreases the normal sensory input to the joints and musculature's proprioceptors.
It would be highly advantageous, and the present invention is directed to, a dynamic shoulder support that allows and facilitates shoulder and elbow motion while providing sufficient protection to prevent subluxation of the glenohumeral joint, allows gravity to stimulate joint proprioceptors at the shoulder and elbow, facilitates shoulder musculature and the elbow extensors, and permits exercise including (1) shoulder abduction or adduction, (2) shoulder flexion or extension, (3) internal or external rotation at the shoulder, and (4) elbow extension or flexion and exerts a constant and firm pressure on the volar surfaces or muscle bellies of spastic muscles, thereby tending to inhibit or decrease the tonus of the muscle by affecting the gamma loop, thereby decreasing the spasticity in those muscles.
In addition, it would be highly advantageous, and the present invention is directed, to a shoulder and arm support that supports the forearm in a neutral position, neither supinated nor pronated, thereby lessening the possibility of a joint contraction in a pronated position.